It is known to make fine glass microfibers having mean fiber diameters below about two microns, and even below one micron, as disclosed in U.S. Pat. No. 4,167,404, which disclosure is hereby included by reference.
In that process glass rods or primaries are remelted and attenuated into very fine fibers having mean fiber diameters below about two microns by high impact jet blasts created by air-gas burners. The fine fibers are entrained in the gaseous stream and are removed by pulling the air through a moving screen where the fibers remain and build up to form a thin blanket while the gases pass through the screen and are exhausted. The blanket of fiber on the moving screen is passed between seals into a zone where there is ambient pressure or positive pressure underneath the screen allowing the fiber to be removed from the screen and wound up on a mandrel. Some densification of the fiber blanket takes place as the blanket winds up on the mandrel due to the weight of the mandrel, and optionally a composting roller, but the blanket is not densified to the extent desired. An optional compacting roller or a weighted mandrel are normally used to increase the density of the fiber roll or mass. However, this extra force applied to the mandrel becomes heavy, or the resultant force causes the collection surface to be deformed and the collection drum to become deformed resulting in high maintenance.